The long term goal of this proposal is to provide Dr. Ana Karina Bedran-Russo, DOS, MS, PhD with the opportunity to develop into a well prepared, competitive and independent young scientist that will combine an active research career with teaching and practice. The applicant's ultimate goal is to improve patient care by contributing to translational research. Additional training in tissue engineering, oral biology and biomaterials obtained during this K08 Mentored Clinician Scientist Award will provide the necessary skills for a dental academic career track within a supportive multidisciplinary environment for the rapid transition of Dr. Bedran- Russo to an independent clinician scientist. Her research and training will be conducted under the guidance of Dr. James Drummond and Dr. Anne George. The applicant will build upon this research to seek additional funding. The research component of this grant aims to investigate the contribution of biochemical modifications to collagen on the properties of dentin and consequently on the durability of adhesive restorative dental treatments. A composite resin restoration last an average of 7 years in posterior teeth at which time failure at the interface is the primary reason given for replacement and accounts for 30-60% of all replaced restorations. The integrity of fibrillar type I collagen is an important issue when bonding to dentin since it is the main tooth component involved during restorative procedures. The hypothesis to be tested is that the artificially formed collagen cross-links in dentin will result in restoration interfaces with improved mechanical properties to withstand degradation over time. The specific aims proposed are: Aim 1. Determine the biochemical properties of dentin following treatment with different crosslinking agents. Biochemical properties (collagen cross-linking analysis - HPLC and immunohistochemical analysis) will be assessed in sound and caries-affected human dentin in both short and long term evaluations. Aim 2: Assess the mechanical properties of the treated dentin (sound and caries-affected) at short-term and long-term evaluations. Stiffness and hardness will be evaluated in specific sites using an atomic force microscope. Ultimate strength of dentin and bond strength of the dentin/restoration interface will be assessed using a universal testing machine. These combined biochemical and mechanical approaches will provide insights to correlate quality of dentin collagen and the long-term durability of restorations.